POS0758 REDUCED CENTRAL NERVOUS SYSTEM DRIVE IN PRIMARY SJÖGREN’S SYNDROME IS ASSOCIATED WITH OBJECTIVE DECLINE IN MOTOR PERFORMANCE AND SELF-REPORTED FATIGUE
Authors: R. Prak, S. Arends, G. M. Verstappen, G. S. Van Zuiden, F. G. M. Kroese, H. Bootsma, I. Zijdewind
Journal: Annals of the Rheumatic Diseases (2022)

Background Fatigue is a major complaint in primary Sjögren’s syndrome (pSS). The importance of fatigue in pSS is demonstrated by its inclusion as one of the three domains of the EULAR Sjögren’s Syndrome Patient Reported Index (ESSPRI) as well as being the primary outcome measure of a large clinical trial. 1 To date, there is no effective treatment for fatigue and more fundamental studies are needed to identify potential targets for therapy. In a conceptual framework, fatigue is defined as a self-reported symptom derived from two attributes: performance fatigability and perceived fatigability (Figure 1). Figure 1. Conceptual framework (adapted from Enoka) 2 Objectives To acquire a better understanding of fatigue in pSS, we investigated objective measures of performance decline and evaluated the relation of self-reported fatigue with performance fatigability and factors modulating perceptions of fatigability. Methods 39 pSS patients and 27 healthy controls were included. To assess performance fatigability, force decline was measured during a sustained (124s) maximal voluntary contraction (MVC) with the index finger abductor muscle, and voluntary muscle activation was indexed using peripheral nerve stimulation superimposed on maximal voluntary contractions. Self-reported fatigue was quantified using the Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS). Pain, depression, and anxiety were assessed using questionnaires and serological inflammatory markers were measured in serum as factors relating to perceived fatigability. Results Self-reported fatigue was significantly higher in pSS than controls (FSS: 4.8 vs. 2.3, p&lt;0.001); 67% of patients and no controls reported significant fatigue (FSS&gt;4). Mean voluntary muscle activation was reduced in pSS compared to controls (81.5% vs. 87.8%, p=0.030). Force decline during the sustained MVC did not differ between groups (60.6% vs. 63.1%, p=0.246). MFIS physical was positively associated with symptoms (ESSPRI pain: ρ=0.51, HADS depression: ρ=0.45 and HADS anxiety: ρ=0.29) and negatively associated with serological inflammatory markers (MxA: ρ=-0.49 and CXCL10: ρ=-0.37). Multivariable linear regression showed that force decline, pain and depression were associated with the MFIS physical domain in pSS (total explained variance of 47%). The inclusion of serological inflammatory markers did not help to explain more variance in this model. Conclusion This study demonstrates that performance fatigability in pSS was compromised by a reduced capacity of the central nervous system to drive the muscle. Furthermore, self-reported fatigue is a multifactorial symptom associated with both performance fatigability and perceived fatigability in patients with pSS. References [1]Bowman et al. Arthritis Rheumatol. 2017;69, 1440–50. [2]Enoka and Duchateau. Med. Sci. Sports Exerc. 2016;48,2228–38. Disclosure of Interests Roeland Prak: None declared, Suzanne Arends: None declared, Gwenny M. Verstappen: None declared, Greetje S. van Zuiden: None declared, Frans G.M. Kroese: None declared, Hendrika Bootsma Speakers bureau: Bristol Myers Squibb, Novartis, Consultant of: Bristol Myers Squibb, Roche, Novartis, Medimmune, Union Chimique Belge, Grant/research support from: Bristol Myers Squibb, Roche, Inge Zijdewind: None declared